Field of the Invention
The present invention relates to an electric propulsion device, and more particularly, it relates to an electric propulsion device including a duct and a rim.
Description of the Background Art
An electric propulsion device including a duct and a rim is known in general. Such an electric propulsion device is disclosed in U.S. Patent Application Publication No. 2012/0251353 and Japanese Patent Laying-Open No. 2013-100013, for example.
The aforementioned U.S. Patent Application Publication No. 2012/0251353 discloses an electric propulsion device including a motor and two propellers. One propeller generates propulsive force in a front-back direction, and the other propeller generates propulsive force in a right-left direction. The two propellers are arranged such that the rotation axes thereof are orthogonal to each other.
The aforementioned Japanese Patent Laying-Open No. 2013-100013 discloses an electric propulsion device including a duct that defines a stator and a rim that defines a rotor rotatable relative to the duct. This electric propulsion device includes a steering shaft that supports the duct so as to turn the duct about a turning axis that intersects with the rotation axis of the rim and a turning actuator that is fixed to the duct and rotates the steering shaft. The turning actuator integrally turns the duct and the rim through the steering shaft.
In the electric propulsion device described in the aforementioned U.S. Patent Application Publication No. 2012/0251353, the direction of generated propulsive force can be changed, but it is necessary to provide at least the two propellers. Therefore, the electric propulsion device is disadvantageously increased in size.
In the electric propulsion device described in the aforementioned Japanese Patent Laying-Open No. 2013-100013, the direction of generated propulsive force can be changed by integrally turning the duct and the rim, but it is necessary to provide the steering shaft. Therefore, the electric propulsion device is increased in size, and hence it is preferable to remedy this problem.